Apparatus for making finned tubing



Jan. 29, 1957 E. H. JOHNSON 2,779,383

APPARATUS FOR MAKING FINNED TUBING Filed May 11, 1954 4 Sheets-Sheet 1 1 229.1 cacao TING MECH ISM I171! er? for fdwirz cfofifltson Jan. 29, 1957 E. H. JOHNSON 2,779,383

APPARATUS FOR MAKING FINNEID TUBING Filed May 11, 1954 4 Sheets-Sheet 2 Jan. 29, 1957 E. H. JOHNSON APPARATUS FOR MAKING FINNED TUBING 4 Sheets-Sheet 5 Filed May 11, 1954 Wm m m 2 M W llt indiilHhlui Jan. 29, 1957 E. H. JOHNSON 2,779,383

APPARATUS FOR MAKING FINNED TUBING Filed May 11, 1954 4 Sheets-Sheet 4 COILING EFFECT DISREGARDED Int/enforfdw/b Johns or? 0 5 4/ w M/ Ca/Wnm/ fiflorneg' Unitiid States Patent O APPARATUS FOR MAKING FINNED TUBING Edwin H. Johnson, Dayton, Ohio, assignor to Jandor Incorporated, Dayton, Ohio, a corporation of Ohio Application May 11, 1954, Serial No. 428,897

3 Claims. (Cl. 153-645) This invention relates to the production of finned tubing of the kind used for heat transfer purposes, and particularly, the invention relates to the production of finned tubing wherein the fin material is applied to the tube in a spiral relationship.

When fin material is to be applied to tubing in a spiral relationship, the difficulty of applying the thin metal fin material in a spiral form so that it has the requisite metal to metal association with the tube is well recognized in the industry, and it is the primary object of the present invention to simplify the production of thermally efficient and low cost heat transfer elements of the spirally finned type, and a related object is to enable the fin-forming operation to be accomplished progressively and under accurately regulated and controlled conditions as the tube advances through the fin forming and applying mechanism so that a tube with the spirally wound fin material firmly and accurately located in the desired relationship thereabout may be readily and easily produced.

Further objects of the present invention are to enable fin material that is exceptionally thin to be employed, to simplify the handling and formation of the fin in its spiral relationship on and with respect to the tube, and to enable this to be accomplished in such a way that the fin material will be accurately located on the tube with a firm gripping action and with the maximum area of mechanical or metal to metal contact with the tube so that the subsequent bonding of the fin material to the tube will in many instances be unnecessary, and so that such mechanical bonding will simplify subsequent metal bonding where this is considered essential or desirable.

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which, by way of illustration, show a preferred embodiment of the present invention and the principle thereof and what I now consider to be the best mode in which I have contemplated applying that principle. Other embodiments of the invention embodying the same or equivalent principle may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.

In the drawings:

Fig. 1 is a face view showing the strip of fin material in its original form and in the corrugated form in which it is fed to the fin forming and applying apparatus;

Fig. 2 is a side elevational view of the finned tube;

Fig. 3 is a cross sectional view of the finned tube;

Fig. 4 is an end elevational view of the forming machine of the present invention as viewed from the right in Fig. 6;

Fig. 5 is a detail view showing a guide member that is included in the machine;

Fig. 6 is a plan view of the fin forming and applying machine;

Fig. 7 is a side elevational view taken partially. in vertical section;

Fig. 8 is a cross sectional view taken substantially along the line 8-8 of Fig. 7 and illustrating the tube advancing or feeding mechanism;

Fig. 9 is a vertical sectional view taken along the line 9--9 of Fig. 7 and illustrating the drive means for the fin guiding and forming rolls;

Fig. 10 is an enlarged and somewhat schematic perspective view of one of the fin guiding and forming rolls and illustrating the change that is made in the fin by such a guiding and forming roll;

Figs. 10A, 10B and 10C are schematic cross sectional views taken along correspondingly numbered section lines in Fig. 10; and

Fig. 11 is a schematic view illustrating the relationship of the guiding and forming rolls with respect to the fin material, it being noted that the coiling efiect of the forming rolls upon the fin material has been disregarded in Fig. 11.

For purposes of disclosure, the invention is herein illustrated as embodied in a finned-tube forming machine 20 that is made up of a pair of stationary standards 21 and 22 that may be secured as by bolts 23 on any suitable base member 24, and the standard 21 constitutes the fin forming and applying portion of the machine, while the mechanism included in the standard 22 constitutes a cooperating advancing or feeding mechanism whereby a tube 25 that is to be finned is advanced longitudinally through the machine 20 in a coordinated relation to the fin forming and applying mechanism. In the course of operation of the machine 20, a continuous spirally formed fin 26 is applied to the tube 25 with a definite lead and with a firm gripping relationship about and with respect to the tube 25 so that the tube 25 with the spiral fin 26 thereon may thereafter be used and handled readily without metal bonding, or if desired, may be subjected to a metal fusing or metal bonding operation or the like in which the fin 26 is joined by a metal bond to the tube 25.

In guiding the tube 25 longitudinally through the standards 21 and 22 of the machine 20, a locating and guiding sleeve 30 is extended through and rotatably mounted in the two standards 21 and 22, such rotative mounting being accomplished by means of needle bearings 31 and 32, Fig. 7, and the sleeve 30 is adapted to be rotated in its bearings and with respect to the standards 21 and 22 by any suitable drive means which may include a drive gear 33 that is shown in dotted outline in Figs. 6 and 7. The gear or other driving means is located on the sleeve 30 to the left of the standard 21, and thus the tube 25 that is to have the fin 26 applied thereto may be fed longitudinally into the left-hand end of the sleeve 30 so as to pass first through the standard 22 and then through the standard 21, and the fin 26 is applied to the tube 25 as the tube 25 passes to the right out of the sleeve 34), Fig. 7, and away from the standard 21 in a right-hand direction.

Before describing the specific way in which the fin 26 is applied to the tube 25, it should be pointed out that this fin 26 is formed from relatively thin, flat, strip material formed from a metal such as aluminum in the desired width and thickness, this fiat strip being identified as the strip 126 in Fig. 1 of the drawings, and the strip 126 is, of course, obtained in a coiled form and is fed through any conventional type of corrugating mechanism 35 to produce a transversely corrugated strip 26C, as shown in Fig. 1. This strip 26C has corrugations C formed therein so that the effective length of the strip 26C is shortened in an amount which is related, as will herein: after be described, to the width of the strip and to the diameter of the tube 25 upon which it is to be spirally wound. Then, in applying the corrugated strip 260 to the tube 25, one edge of the strip 26C is again flattened in a progressive manner so as to increase the length of thisxone edge of the strip 26C as at 26F, Figs. 2 to 4, 1.0 and 11 and cause the same to assume a spirally coiled relationship, the strip 260 being fully guided and controlled in a predetermined manner with respect to the tube 25 as such forming of the strip progresses.

The lengthening of the one side or border edge 26? of the strip 26C is performed along the edge that is to constitute the outer edge of the fin 26 in the final product, and this lengthening deforms or stretches the corrugations C to a considerable extent along the bordering edge 26F of the strip, while adjacent the inner edge of the fin, the corrugations are compressed or narrowed, depending to some extent upon the diameter of the tube that is being finned. Thus the corrugations retain their original form and spacing only at points substantially midway between the inner edge of the border 26? and the inner edge of the fin. The flattening of the her ering edge 26F of the strip is attained in such a way as to accomplish what may be termed a cold Working action upon the strip 260 and this cold working action permanently stretches the corrugations C adjacent to the fiat tened border edge 26F so that when the operation is completed, the corrugations are relatively wide adjacent to the fiat border edge 26F, Fig. A and are progressively narrower toward the other or inner edge of the strip 26C, as shown in Figs. 10B and 10C. Preferably, the original spacing of the corrugations and the amplitude or depth thereof are so chosen with respect to the width of the strip and the diameter of the tube that when the flattening and cold working of the bordering edge F has been completed, the strip will tend to assume an internal diameter, in its spiral form, which is somewhat less than the outer diameter of the tube 25, thus to cause the coiled fin 26 to firmly grip the tube 25 With a uniform force so that the fin maintains its proper form and has a mechanical clamping action on the tube 25 so as to be held in place securely with the maximum of metal to metal contact with the tube, and this eliminates the need in many instances for a subsequent metal bonding of the fin 26 to the tube 25, or facilitates such an operation where this is considered desirable.

In accomplishing the forming and coiling of the strip 26C about the tube 25, the tube is rotated at a constant speed and is advanced in a predetermined relationship to the rotative movement so as to establish the desired lead in the spiral formation and application of the fin 26. Such advancing or feeding means for the tube 25 may take different forms, and in the present instance, a preferred form of advancing means 38 is shown as being mounted within the standard 22 so as to be operated as an incident to rotation of the sleeve 30, and the advancing means serves also to impart the desired rotative movement to the tube 25. Such means will be described in further detail hereinafter.

The forming means for flattening and cold working the outer border edge of the strip 26C to afford the fiat outer border area 26F are afforded under the present invention by a series of driven forming rolls that are mounted on the right-hand end face of the standard 21 and are disposed in a closed spaced series about the rotative axis of the sleeve so that these rolls 40 act successively on the corrugated strip 26C as it is fed and guided around the rotating tube 25. The forming rolls 40 serve to enclose and guide the fin material during the entire forming and applying operation, thus to simplify the starting of the coiling operation while at the same time assuring continued proper operation of the machine. The forming rolls 40 have a form and positioning with respect tothe axis of the sleeve 30 that is related, as will hereinafter be described, to the lead that is to be attained in the. spiral fin 26, and which is also related to the original thickness and the corrugated thickness of the strip that is being used to form the fin 26.

As shown in Figs. 4, 6, and 7, the corrugated strip 260 is advanced in a plane that is substantially perpendicular to the axis of the sleeve 30 and which is tangential to the tube 25 as this tube emerges from the right-hand end of the sleeve 30, Fig. 7, and the several forming rolls 40-1 to 40-10 are disposed in circumferential series about the axis of the sleeve 30 so that these rolls 40 will act successively upon the outer bordering edge of the corrugated strip 26C. The rolls 40-1 to 40-10 are generally similar in form and have an annular tapered groove 41 therein, and at the bottom of such tapered groove 41, a narrow groove 42 or" rectangular cross section is formed. The angular groove 41 serves primarily as a guiding means so that the edge of the strip 26C will be guided into the rectangular groove or throat 42 of the roll, and the rolls 40-1 to 40-9 have the throats thereof formed so as to be progressively narrower, the roll 40-10 having a throat 42 that is of the same width as the throat of the roll 40-9. Where a fin material .010 inch in thickness is used with the amplitude of the corrugations C about .065 inch, I have found that the first roll 40-1 may have its throat 42 formed with a width of .050 inch, and the succeeding rolls 40-2 to 40-9 may have their throats 42 reduced successively by .005 inch until the final two rolls 40-9 and 40-10 have a throat width of .010 inch.

The several guiding and forming rolls 40-1 to 40-10 are arranged so as to be offset in a longitudinal direction, one with respect to the other, so that the longitudinal positions of these forming roll-s 40 are coordinated with the lead that is to be established in the fin 26, it being recalled that this lead is established by the drive or advancing means 38 that are mounted within the standard 22 of the machine. Thus Where the lead is to be .125 inch, the rolis 40-1 to 40-10, when angularly spaced 30 degrees apart, may be progressively ofiset .010 inch or an amount equal to the lead divided by the angular roll spacing in degrees multiplied by 360 degrees, as indicated in Fig. ll.

To simplify the initial feeding of the strip 26C into the forming rolls 40-1 to 40-10, a stationary guide is preferably provided, this guide being mounted on one element 46D of an entry guide 46. This entry guide 46 has another member 46A that has the member 4613 secured thereto and an entry slot 468 is formed between the two members 46A and 4613. The entry guide 46 is mounted by means of bracket members 47 on the standard 21 and the end of the corrugated strip 26C is fed through the slot 468 and along one side face of the guide 45 so that the initial entry of the strip 26C into the forming slots 42 is assured. As shown in Figs. 4 and 6, the strip 26C passes along the face of the guide 45 that is adjacent to the standard 21.

The present embodiment of the invention affords ten rolls 40 that are spaced 30 degrees apart around the axis of the sleeve 30, thus to accomplish the forming operation in substantially 270 degrees of movement of the strip 26 about the tube 25, and the other degrees that is aiforded between the rolls 40-1 and 40-10 affords space for entry of the strip 26 C and for the proper support of the guide 45. With this arrangement the fin strip 26C is completely housed and accurately guided until it has been engaged with more than half of the circumference of the tube 25, and until it has attained a firm mechanical grip on the tube 25.

The several guide and forming rolls 40 are supported on drive shafts 50 that extend through the standard 21 at appropriate points about the axis of the sleeve 30, and these shafts 50 are supported by bearings 51 in the standard 21. At their right-hand ends, as viewed in Figs. 6 and 7 of the drawings, the shafts 50 are in most instances provided with spacing collars 52, and at the righthand ends, the forming rollers 40 are mounted in fixed or driven relationship with respect to the shafts 50. At their other or left-hand ends, as viewed in Fig. 7, the shafts 50 have pinions 54 fixed thereon, these pinions being of the same size, and being engaged with a drive gear 55' that is secured as by means of a screw 56 to the I sleeve 30. The gear 50 and a flange 30F on the righthand end of the sleeve 30 serve to hold the sleeve 30 in the proper endwise position. The sleeve 30, in its rotative movement imparts constant rotating movement to all of the guiding and forming rolls 40, and under the present invention, the forming rolls 40 are driven at a speed such that there is a pronounced slipping of these rolls on and with respect to the strip 260. Thus, a constant forward or advancing drive is imparted to the strip 26C, while at the same time a working or ironing or cold working action is applied constantly and progressively to the strip 26C in the border 26]? thereof. In the present case this is accomplished by making the pinions 54 of a size that is substantially equal to the inner diameter of the forming grooves 42 of the rolls 40.

The advancing means 38 is best illustrated in Figs. 7 and 8 of the drawings, and are afforded by a plurality of rolls 60 and 60D that are mounted in a mounting bracket 61 that is secured to the sleeve 30 by means of a screw 62 so as to rotate with the sleeve 30. The bracket 61 serves to support the several rolls 60 and 60D in circumferentially spaced relationship so that the peripheries of these feed rolls extend through slots 63 formed in the sleeve 30, and thus the rolls 60 and 60D engage the tube 25 that is disposed within the sleeve 30. In the present instance, two rolls 60 and one roll 60]) are afforded, and these are spaced apart so as to engage the tube 25 at equal points about the periphery thereof. The two rolls 60 serve as idler rolls, while the roll 60D constitutes a driven roll, and means are afforded for driving the roll 60D at a rate that is coordinated with the relative rate of the sleeve 30. The several feed rolls 60 and 60D have their outer annular corners bevelled so as to afford relatively narrow driving edges 160 and 160D, and this is done to assure a proper or non-slipping engagement of the rolls 60D and 60 with the tube 25, thus to cause the tube 25 to be rotated and advanced endwise in a coordinated relation that corresponds to the lead that is to be attained in the fin 26.

In the present instance, the roll 60D has a bevel gear 64 fixed thereto, and this bevel gear 64 meshes with another bevel gear 65 that is fixed to and mounted on the axis of a spiral pinion 66, the spiral pinion also being mounted in the bracket 61. The spiral pinion 66 is arranged to engage a spiral thread 68 which is, in reality, nothing more than an internal worm gear formed on the cylindrical inner surface of the standard 22 on an axis concentric with the axis of the sleeve 30. The arrangement is such that the pinion 66 moves with the sleeve 39 and the bracket 61 about the axis of the sleeve, as the sleeve 30 is rotated, and in each full rotation of the sleeve 30, the worm gear or spiral gear 66 is advanced in an amount sufficient to feed the tube 25 forward in an amount equal to the lead that is desired in the fin 26.

Since the several forming rolls 40-1 to lit-ii) are in a closely spaced series that extends about substantially more than half of the periphery of the tube 25, the advancing strip 26C is fully guided and controlled throughout its entire forming and applying operation, and such contr-ol is further improved through the provision of the stationary guide strip 45. During this fully guided movement, the progressive cold working and forming of the outer border portion 26F of the tin material causes the form of the corrugations C to be modified, as will be evident in Figs. A, 10B and 10C of the drawings, and when the forming operations are completed in respect to any particular portion of the fin, the base portion of the fin that engages the tube is relatively wide so that the fin is, by its own form and coiled tension, held in the desired upright relationship with respect to the tube 25, The gradual and progressive working of the fin material until it tends to assume an internal diameter somewhat smaller than the external diameter of the tube 25 assures firm mechanical gripping action of the coiled fin material upon the tube, and the undulating broad inner face of the fin material is thus firmly seated against the tube 25 with a large area metal to metal contact that in most instances results in a heat transfer action that so closely approaches the heat transfer that is gained when a metal bonding operation is used that such a metal bonding operation is, in fact, unnecessary in many instances where the present finned tubing is to be employed. It should be understood, of course, that where the absolute maximum of heat transfer between the tube and the fin is desired, such a metal bonding operation may be performed with the present finned tubing, and the metal bonding operation, whether it be performed by soldering, brazing or the like, is facilitated because of the even or uniform coiled tension of the fin and the firm mechanical bond that has been established between the fin and the tube.

From the foregoing description, it will be apparent that the present invention materially simplifies the production of finned heat transfer tubing and assures the production of such tubing with the maximum of heat transfer capabilities. Furthermore, it will be clear that because of the controlled forming and applying operations that are utilized under the present invention, an extremely thin material may be employed, while at the same time assuring accuracy and permanency of formation of the finned tubing. It will also be evident that because of the uniform and firm gripping action that is attained between the fin material and the tube under the present invention, an unusually efficient metal to metal contact is established between the fin material and the tube, and this not only makes it unnecessary in many instances to metal bond the fins to the tube, but also facilitates such metal bonding operations where this is considered necessary or desirable.

Thus, while I have illustrated and described the preferred embodiment of my invention, it is to be understood that this ,is capable of variation and modification, and 1 therefore do not Wish to be limited to the precise details set forth, but desire to avail myself of such changes and alterations as fall within the purview of the following claims.

I claim:

1. In a machine for making finned heat transfer tubing, driving means for imparting coordinated rotating and longitudinal advancing movements to a tube that is to be finned, means for feeding a transversely corrugated thin metal strip into a tangential relation to such a tube and in a plane substantially perpendicular to such tube, a plurality of rotative circumferentially grooved forming and guiding rolls disposed in a closely spaced series extending about the axis of rotation of the tube for substantially more than degrees and offset axially in a progressive relation conforming with the lead relation established by said driving means, said rolls having th;v circumferential grooves thereof formed of progressively narrower widths to progressively flatten the corrugations in the outer border portion of the corrugated metal strip, and means operated by said driving means for driving said rolls at a common advancing speed effective to produce a slipping and ironing action on the strip to cold work the engaged border of the strip, while at the same time imparting advancing forces thereto.

2. In a machine for making finned heat transfer tubing, a pair of stationary standards, a sleeve rotatably journalled in said standards and through which a tube may extend, means for rotating said sleeve, common rotating and advancing means carried by said sleeve and engaging a tube to rotate the same with the sleeve and impart a predetermined axial movement to the tube, said common means including a plurality of feed rollers carried by said sleeve in circumferentially spaced relationship thereto and projecting through the sleeve to engage a tube therewithin, each of said feed rollers being journalled for rotation about an axis disposed in a plane perpendicular to the axis of the sleeve and said rollers being disposed within the confines of one of said stationary standards, a gear fixed to one of said rollers and said one standard being internally geared and having driving engagement with said roller gear for rotating said one roller as the sleeve is rotated Within the one standard to impart longitudinal movement to the tube, means for feeding a transversely corrugated thin metal strip into a tangential relation to the tube adjacent one end of the sleeve and in a plane substantially perpendicular to such tube, a lurality of circumferentially grooved forming and guiding rolls mounted upon the other standard for rotation about axes parallel to the axis of said sleeve and said rolls being ofiset axially in a progressive relation conforming with the lead relation established by said common means, said sleeve having an external gear fixed thereto and each of said guiding rolls having a gear fixed thereto in mesh with the external gear on the sleeve whereby the guide rolls are driven in response to rotation of the sleeve, said rolls having the circumferential grooves thereof formed of progressively narrower widths to progressively flatten the corrugations in the outer border portion of the metal strip, and the geared relation between the guide rolls and the external sleeve gear bciug such as to drive the guide rolls at a common ad vancing speed to engage the strip at a speed greater than the speed of the tube to produce a slipping and ironing action on the strip to cold work the engaged border of the same, while at the same time imparting advancing forces thereto.

3. In a machine for making finned heat transfer tubing, driving means for imparting coordinated rotating and longitudinal advancing movements to a tube that is to be finned, means for feeding a transversely corrugated thin metal strip into a tangential relation to such a tube and in a plane substantially perpendicular to such tube, a plurality of rotative circumferentially grooved forming and guiding rolls disposed aboutthe axis of roration of the tube and offset axially in aprogressive relation conforming with the lead relation established by said driving means, said rolls having the circumferential grooves thereof formed of substantially the same depth and progressively narrower widths to progressively reduce the amplitude of the corrugations always substantially in the same outer border portion of the corrugated metal strip, and means driving said rolls at a common advancing speed to engage the strip at a speed greater than the speed of the tube to produce a slipping and ironing action on the strip to cold work the engaged border of the strip while at the same time imparting advancing forces thereto.

References Cited in the file of this patent UNITED STATES PATENTS 1,570,117 Zimmermann M Jan. 19, 1926 1,840,317 Horvath Jam 12, 1932 1,992,297 Dewald Feb. 26, 1935 1,997,197 Nigro Apr. 9, 1935 2,532,239 Newlin Nov. 28, 1950 2,635,571 Edwards Apr. 21, 1953 2,661,525 Edwards Dec. 8, 1953 FOREIGN PATENTS 324,182 France Mar. 25, 1903 401,868 Germany Sept. 10, 1924 453,710 Germany Dec. 13, 1927 658,097 Germany Mar. 22, 1938 

